DSpace at VNU: Study of psi(2S) production and cold nuclear matter effects in pPb collisions at root s(NN)=5 TeV

DSpace at VNU: Study of psi(2S) production and cold nuclear matter effects in pPb collisions at root s(NN)=5 TeV tài liệ...

Published for SISSA by Springer Received: January 29, 2016 Accepted: February 29, 2016 Published: March 18, 2016 The LHCb collaboration E-mail: yangzhw@tsinghua.edu.cn Abstract: The production of ψ(2S) mesons is studied in dimuon final states using protonlead (pPb) collision data collected by the LHCb detector The data sample corresponds to an integrated luminosity of 1.6 nb−1 The nucleon-nucleon centre-of-mass energy of the √ pPb collisions is sN N = TeV The measurement is performed using ψ(2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and −5.0 < y < −2.5 in the nucleon-nucleon centre-of-mass system The forward-backward production ratio and the nuclear modification factor are determined for ψ(2S) mesons Using the production cross-section results of ψ(2S) and J/ψ mesons from b-hadron decays, √ the b¯b cross-section in pPb collisions at sN N = TeV is obtained Keywords: Particle and resonance production, Quarkonium, Relativistic heavy ion physics, Heavy Ion Experiments, Heavy-ion collision ArXiv ePrint: 1601.07878 Open Access, Copyright CERN, for the benefit of the LHCb Collaboration Article funded by SCOAP3 doi:10.1007/JHEP03(2016)133 JHEP03(2016)133 Study of ψ(2S) production and cold nuclear matter √ effects in pPb collisions at sN N = TeV Contents Detector and datasets 3 Event selection and cross-section determination Signal extraction and efficiencies Systematic uncertainties 6 Results 6.1 Cross-sections 6.2 Cold nuclear matter effects 7 Conclusions 11 The LHCb collaboration 16 Introduction The quark-gluon plasma (QGP) is a state of matter with asymptotically free partons, which is expected to exist at extremely high temperature and density It is predicted that heavy quarkonium production will be significantly suppressed in ultrarelativistic heavyion collisions if a QGP is created [1] This suppression is regarded as one of the most important signatures for the formation of the QGP Heavy quarkonium production can also be suppressed in proton-nucleus (pA) collisions, where hot nuclear matter, i.e QGP, is not expected to be created and only cold nuclear matter (CNM) effects exist Such CNM effects include: initial-state nuclear effects on the parton densities (shadowing); coherent energy loss consisting of initial-state parton energy loss and final-state energy loss; and final-state absorption by nucleons, which is expected to be negligible at LHC energies [2– 9] The study of pA collisions is important to disentangle the effects of QGP from those of CNM, and to provide essential input to the understanding of nucleus-nucleus collisions Nuclear effects are usually characterized by the nuclear modification factor, defined as the production cross-section of a given particle per nucleon in pA collisions divided by that in proton-proton (pp) collisions, RpA (y, pT , √ sNN ) ≡ √ d2 σpA (y, pT , sNN )/dydpT , √ A d2 σpp (y, pT , sNN )/dydpT –1– (1.1) JHEP03(2016)133 Introduction where A is the atomic mass number of the nucleus, y (pT ) is the rapidity (transverse √ momentum) of the produced particle, and sNN is the centre-of-mass energy of the protonnucleon system Throughout this paper, y always indicates the rapidity in the nucleonnucleon centre-of-mass system RFB (y, pT , √ sNN ) ≡ √ σpPb (+|y|, pT , sNN ) √ σpPb (−|y|, pT , sNN ) (1.2) The advantage of measuring this ratio is that it does not rely on knowledge of the production cross-section in pp collisions Furthermore, part of the experimental systematic uncertainties and theoretical scale uncertainties cancel in the ratio The measurements in the fixed-target pA collisions [10–12] showed stronger suppression at central rapidity for ψ(2S) mesons than for J/ψ mesons, while at forward rapidity the suppressions were compatible within large uncertainties The PHENIX experiment made similar observations at central rapidity in dAu collisions at RHIC [18] The ALICE experiment measured the ψ(2S) suppression in the forward and backward rapidity regions in pPb collisions at the LHC [21] Nuclear shadowing and energy loss predict equal suppression of J/ψ and ψ(2S) mesons, and so cannot explain the observations One explanation for the fixed-target results is that the charmonium states produced at central rapidity spend more time in the medium than those at forward rapidities; therefore the loosely bound ψ(2S) mesons are more easily suppressed than J/ψ mesons at central rapidity [22–24] In this picture it is expected that the charmonium states will spend a much shorter time in the CNM at LHC energies than at lower energies, leading to similar suppression for ψ(2S) and J/ψ mesons even at central rapidity The excellent reconstruction resolution of the LHCb detector for primary and secondary vertices [25] provides the ability to separate prompt ψ(2S) mesons, which are produced directly from pp collisions, from those originating from b-hadron decays (called “ψ(2S) from b” in the following) In this analysis, the production cross-sections of prompt √ ψ(2S) mesons and ψ(2S) from b are measured in pPb collisions at sNN = 5.02TeV, approximated in the following to TeV The nuclear modification factor RpPb and the forward-backward production ratio RFB are determined in the range 2.5 < |y| < 4.0 Using the production cross-sections of ψ(2S) from b and J/ψ from b, the bb production crosssection in pPb collisions is obtained –2– JHEP03(2016)133 The suppression of quarkonium and light hadrons at large rapidity has been observed in pA collisions [10–13] and in deuteron-gold collisions [14–18] The proton-lead (pPb) collisions recorded at the LHC in 2013 enable the study of CNM effects at the TeV scale With these pPb data, the production cross-sections of prompt J/ψ mesons, J/ψ mesons from b-hadron decays, and Υ mesons were measured, and the CNM effects were studied by determining the nuclear modification factor RpPb and the forward-backward production ratio RFB [19, 20] Working in the nucleon-nucleon rest frame, the “forward” and “backward” directions are defined with respect to the direction of the proton beam The ratio RFB is defined as Detector and datasets Event selection and cross-section determination The measurement of ψ(2S) production is based on the method described in refs [19, 34, 35] The ψ(2S) candidates are reconstructed using dimuon final states from events with at least –3– JHEP03(2016)133 The LHCb detector [25, 26] is a single-arm forward spectrometer covering the pseudorapidity range < η < 5, designed for the study of particles containing b or c quarks The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the pPb interaction region, a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about Tm, and three stations of silicon-strip detectors and straw drift tubes placed downstream of the magnet The tracking system provides a measurement of momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at 200 GeV/c The minimum distance of a track to a primary vertex, the impact parameter, is measured with a resolution of (15 + 29/pT ) µm, where pT is the component of the momentum transverse to the beam, in GeV/c Different types of charged hadrons are distinguished using information from two ring-imaging Cherenkov detectors Photons, electrons and hadrons are identified by a calorimeter system consisting of scintillating-pad and preshower detectors, an electromagnetic calorimeter and a hadronic calorimeter Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers The online event selection is performed by a trigger, which consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which applies a full event reconstruction With the proton beam travelling in the direction from the vertex detector to the muon system and the lead beam circulating in the opposite direction, the LHCb spectrometer covers forward rapidities With reversed beam directions backward rapidities are accessible The data sample used in this analysis is collected from the pPb collisions in early 2013, corresponding to an integrated luminosity of 1.1 nb−1 (0.5 nb−1 ) for forward (backward) collisions The instantaneous luminosity was around × 1027 cm−2 s−1 , five orders of magnitude below the nominal LHCb luminosity for pp collisions Therefore, the data were taken using a hardware trigger which simply rejected empty events The software trigger for this analysis required one well-reconstructed track with hits in the muon system and pT greater than 600 MeV/c √ Simulated samples based on pp collisions at s = TeV are used to determine the acceptance and reconstruction efficiencies The simulation samples are reweighted so that the track multiplicity distribution reproduces the experimental data of pPb collisions at √ s = TeV In the simulation, pp collisions are generated using Pythia [27] with a specific LHCb configuration [28] Decays of hadronic particles are described by EvtGen [29], in which final-state radiation is generated using Photos [30] The interaction of the generated particles with the detector, and its response, are implemented using the Geant4 toolkit [31, 32] as described in ref [33] one primary vertex The tracks should be of good quality, have opposite sign charges and be identified as muons with high pT The two muon tracks are required to originate from a common vertex with good vertex fit quality, and the reconstructed ψ(2S) mass should be in the range ±145 MeV/c2 around the known ψ(2S) mass [36] Due to the small size of the data sample, only one-dimensional differential cross-sections are measured The differential production cross-section of ψ(2S) mesons in a given kinematic bin is defined as dσ N = , (3.1) dX L × B × ∆X Signal extraction and efficiencies The numbers of prompt ψ(2S) and ψ(2S) from b in each kinematic bin are determined from an extended unbinned maximum likelihood fit performed simultaneously to the distributions of the dimuon invariant mass Mµµ and the pseudo proper decay time tz [34], defined as (zψ − zPV ) × Mψ tz = , (4.1) pz where zψ is the position of the ψ(2S) decay vertex along the beam axis, zPV that of the primary vertex refitted after removing the two muon tracks from the ψ(2S) candidate, pz the z component of the measured ψ(2S) momentum, and Mψ the known ψ(2S) mass [36] The invariant mass distribution of the signal in each bin is modelled by a Crystal Ball (CB) function [38], where the tail parameters are fixed to the values found in simulation and the other parameters are allowed to vary For differential cross-section measurements, the sample size in each bin is very small Therefore, in order to stabilise the fit, the mass resolution of the CB function is fixed to the value obtained from the J/ψ sample, scaled by the ratio of the known ψ(2S) and J/ψ masses [36] The invariant mass distribution of the combinatorial background is described by an exponential function with variable slope parameter The signal distribution of tz can be described [39] by a δ-function at tz = for prompt ψ(2S) and an exponential function for the component of ψ(2S) from b, both –4– JHEP03(2016)133 where X denotes pT or y, N is the efficiency-corrected number of ψ(2S) signal candidates reconstructed with the dimuon final state in the given bin of X, ∆X is the bin width, L is the integrated luminosity, and B is the branching fraction of the ψ(2S) → µ+ µ− decay, B(ψ(2S) → µ+ µ− ) = (7.9 ± 0.9) × 10−3 [36] Assuming lepton universality in electromagnetic decays, this branching fraction is replaced by that of the ψ(2S) → e+ e− , which has a much smaller uncertainty, B(ψ(2S) → e+ e− ) = (7.89 ± 0.17) × 10−3 [36] The integrated luminosity of the data sample used in this analysis was determined using a van der Meer scan, and calibrated separately for the pPb forward and backward samples [37] The kinematic region of the measurement is pT < 14 GeV/c and 1.5 < y < 4.0 (−5.0 < y < −2.5) for the forward (backward) sample For the single differential crosssection measurements, the transverse momentum range pT < 14 GeV/c is divided into five bins with edges at (0, 2, 3, 5, 7, 14) GeV/c The rapidity range is divided into five bins of width ∆y = 0.5 LHCb 1.5 < y < 4.0 pPb(Fwd) sNN = TeV p T < 14 GeV/c Candidates / (10 MeV/ c 2) Candidates / (10 MeV/ c 2) 250 200 150 100 50 LHCb −5.0 < y < −2.5 pPb(Bwd) sNN = TeV p T < 14 GeV/c 100 80 60 40 20 3700 3800 M µµ [MeV/ c 2] Candidates / ps 3600 104 LHCb 103 pPb(Fwd) sNN = TeV 1.5 < y < 4.0 102 3600 3700 104 LHCb 103 pPb(Bwd) sNN = TeV −5.0 < y < −2.5 102 p T < 14 GeV/c p T < 14 GeV/c 10 10 1 -5 3800 M µµ [MeV/ c 2] 10 t z [ps] -5 10 t z [ps] Figure Projections of the fit results to (top) the dimuon invariant mass Mµµ and (bottom) the pseudo proper decay time tz in (left) pPb forward and (right) backward data In all plots the total fitted function is shown by the (black) solid line, the combinatorial background component is shown as the (green) hatched area, the prompt signal component by the (blue) shaded area, and the b-component by the (red) light solid line convolved with a Gaussian resolution function The width of the resolution function and the slope of the exponential function are free in the fit The background distribution of tz in each kinematic bin is modelled with an empirical function determined from sidebands of the invariant mass distribution Figure shows projections of the fit to Mµµ and tz for the full pPb forward and backward samples The combinatorial background in the backward region is higher than that in the forward region, because the track multiplicity in the backward region is larger The mass resolution is 13 MeV/c2 for both the forward and backward samples The total estimated signal yield for prompt ψ(2S) mesons in the forward (backward) sample is 285 ± 34 (81 ± 23), and that for ψ(2S) from b in the forward (backward) sample is 108 ± 16 (21 ± 8), where the uncertainties are statistical only The efficiency-corrected signal yield N is obtained from the sum of wi /εi over all candidates in the given bin The weight wi is obtained with the sPlot technique using Mµµ and tz as discriminating variables [40] The total efficiency εi , which depends on pT and y, includes the geometrical acceptance, the reconstruction efficiency, the muon identification efficiency, and the trigger efficiency The acceptance and reconstruction efficiencies are determined from simulation, assuming that the produced ψ(2S) mesons are unpolarised The efficiency of the muon identification and the trigger efficiency are obtained from data using a tag-and-probe method as described below –5– JHEP03(2016)133 Candidates / ps 120 Source Forward from b inclusive prompt 1.5 1.3 1.9 1.9 2.2 1.5 3.8–6.9 1.5 1.3 1.9 1.9 2.2 1.5 0.3–3.9 1.5 1.3 1.9 1.9 2.2 1.5 3.2–8.2 1.5 1.3 1.9 2.1 2.2 1.5 9.2–10 1.5 1.3 1.9 2.1 2.2 1.5 16–20 1.5 1.3 1.9 2.1 2.2 1.5 3.0–5.4 0.7 0.6–10 1.6–12 0.7 0.4–10 0.3–92 0.7 0.2–9.8 0.1–18 1.7 1.4 1.4–7.8 1.7 2.4 8.5–29 1.7 0.7–23 0.1–17 Correlated between bins Track reconstruction Muon identification Trigger Luminosity Branching fraction Track quality and radiative tail Mass fit Uncorrelated between bins Multiplicity reweighting Simulation kinematics tz fit Backward from b inclusive Table Summary of the relative systematic uncertainties on cross-section measurements (%) Systematic uncertainties Several sources of systematic uncertainties affecting the production cross-section measurements are discussed in the following and summarised in table The uncertainty on the muon track reconstruction efficiency is studied with a datadriven tag-and-probe method, using a J/ψ sample in which one muon track is fully reconstructed while the other one is reconstructed using only specific sub-detectors [41] Taking into account the difference of the track multiplicity distribution between data and simulation, the total uncertainty is found to be 1.5% The uncertainty due to the muon identification efficiency is assigned to be 1.3% for both the forward and backward samples as obtained in the J/ψ analysis in pPb collisions [19] It is estimated using J/ψ candidates reconstructed with one muon identified by the muon system and the other identified by selecting a track depositing the energy of a minimumionising particle in the calorimeters The trigger efficiency is determined from data using a sample unbiased with respect to the trigger decision The corresponding uncertainty of 1.9% is taken as the systematic uncertainty due to the trigger efficiency To estimate the uncertainty due to reweighting the track multiplicity in simulation, the efficiency is calculated without reweighting The difference between cross-sections calculated with these two efficiencies is considered as the systematic uncertainty, which is less than 0.7% in the forward sample, and about 1.7% in the backward sample The possible difference of the pT and y spectra inside each kinematic bin between data and simulation can introduce a systematic uncertainty To estimate the size of this effect the acceptance and reconstruction efficiencies have been checked by doubling the number of bins in pT or in y The difference from the nominal binning scheme is taken as systematic uncertainty, which is 0.2% − 10% (0.7% − 23%) in the forward (backward) sample For the backward sample the separation into prompt ψ(2S) and ψ(2S) from b was not done in bins of pT and y due to the limited sample size –6– JHEP03(2016)133 prompt prompt [µb] from b [µb] inclusive [µb] Forward (+1.5 < y < +4.0) 138 ± 17 ± 53.7 ± 7.9 ± 3.6 192 ± 19 ± 10 Backward (−5.0 < y < −2.5) 93 ± 25 ± 10 20.2 ± 8.0 ± 4.3 113 ± 26 ± 11 Forward (+2.5 < y < +4.0) 65 ± 10 ± 21.4 ± 4.5 ± 1.1 86 ± 11 ± Backward (−4.0 < y < −2.5) 76 ± 23 ± 10 13.8 ± 6.9 ± 5.7 90 ± 24 ± 12 Table Integrated production cross-sections for prompt ψ(2S), ψ(2S) from b, and inclusive ψ(2S) in the forward region and the backward region The pT range is pT < 14 GeV/c The first uncertainty is statistical and the second is systematic 6.1 Results Cross-sections The differential cross-sections of prompt ψ(2S), ψ(2S) from b and inclusive ψ(2S) in the pPb forward region as functions of pT and y are shown in figure The differential crosssections of inclusive ψ(2S) in the pPb backward region as functions of pT and y are shown in figure As stated in section 5, for the differential production cross-section in the backward data sample, no attempt is made to separate prompt ψ(2S) and ψ(2S) from b due to the small statistics However, these two components are separated for the integrated production cross-sections All these cross-sections decrease with increasing |y| The integrated production cross-sections for prompt ψ(2S), ψ(2S) from b, and their sum representing inclusive ψ(2S), are given in table To determine the forward-backward production ratio RFB , the integrated production cross-sections in the common rapidity region, 2.5 < |y| < 4.0, are also given in the table The production cross-sections, σ(bb), of the bb pair can be obtained from σ(bb) = σ(ψ(2S) from b)/2fb→ψ(2S) = σ(J/ψ from b)/2fb→J/ψ , (6.1) where fb→ψ(2S) (fb→J/ψ ) indicates the production fraction of b → ψ(2S)X (b → J/ψ X) The world average values are fb→J/ψ = (1.16 ± 0.10) × 10−2 and –7– JHEP03(2016)133 The luminosity is determined with an uncertainty of 1.9% (2.1%) for the pPb forward (backward) sample [37] The uncertainty on the ψ(2S) → µ+ µ− branching fraction is 2.2% The combined uncertainty related to the track quality, the vertex finding and the radiative tail is estimated to be 1.5% The uncertainty due to modelling the invariant mass distribution is estimated by using the signal shape from simulation convolved with a Gaussian function, or by replacing the exponential function by a second-order polynomial The maximum differences from the nominal results are taken as the systematic uncertainties due to the mass fit To estimate the corresponding systematic uncertainty on the differential production cross-section due to the fixed mass resolution, the mass resolution is shifted by one standard deviation It is found that this uncertainty is negligible The uncertainty due to modelling the tz distribution is estimated by fitting the signal sample extracted from the sPlot technique using the invariant mass alone as the discriminating variable 10 dσ/d y [µb] Inclusive ψ(2S ) Prompt ψ(2S ) ψ(2S ) from b 200 Inclusive ψ(2S ) Prompt ψ(2S ) ψ(2S ) from b LHCb pPb(Fwd) sNN = TeV 150 1.5 < y < 4.0 T dσ/d p [µb/(GeV/ c )] LHCb pPb(Fwd) sNN = TeV p < 14 GeV/c T 100 10 50 10 1.5 p [GeV/c ] 2.5 3.5 T y T LHCb pPb(Bwd) sNN = TeV 102 dσ/d y [µb] dσ/d p [µb/(GeV/ c )] Figure Differential cross-section of ψ(2S) meson production as a function of (left) pT and (right) y in pPb forward collisions The (black) dots represent inclusive ψ(2S), the (blue) triangles indicate prompt ψ(2S), and the (red) squares show ψ(2S) from b The error bars indicate the total uncertainties Inclusive ψ (2S) 200 LHCb pPb(Bwd) sNN = TeV Inclusive ψ (2S) 150 − 5.0 < y < − 2.5 p < 14 GeV/c T 10 100 50 0 10 p [GeV/c ] T 2.5 3.5 4.5 −y Figure Differential cross-section of ψ(2S) meson production as a function of (left) pT and (right) y in pPb backward collisions The error bars indicate the total uncertainties fb→ψ(2S) = (2.83 ± 0.29) × 10−3 [36] The production cross-sections σ(bb) obtained from the results of J/ψ and ψ(2S) from b are shown in table The results of the bb crosssections obtained from ψ(2S) from b are consistent with those from J/ψ from b In the combination of the results the partial correlation between fb→ψ(2S) and fb→J/ψ is taken into account The systematic uncertainties due to the muon identification, the tracking efficiency, and the track quality are considered to be fully correlated The systematic uncertainties due to the luminosities are partially correlated The averaged results are also shown in table 6.2 Cold nuclear matter effects Cold nuclear matter effects on ψ(2S) mesons can be studied with the production crosssections obtained in the previous section As defined in eq (1.2), the forward-backward production ratio, RFB , can be determined with the cross-sections in the common rapidity –8– JHEP03(2016)133 σFwd (bb) [mb] ψ (pT < 14 GeV/c, 1.5 < σBwd (bb) [mb] yψ ψ (pT < 14 GeV/c, −5.0 < y ψ < −2.5) < 4.0) ψ(2S) 9.49 ± 1.40 ± 0.64 ± 0.97 3.57 ± 1.41 ± 0.76 ± 0.37 J/ψ 7.16 ± 0.18 ± 0.40 ± 0.62 5.09 ± 0.29 ± 0.53 ± 0.44 7.43 ± 0.56(uncorr) ± 0.49(corr) 4.87 ± 0.62(uncorr) ± 0.32(corr) Averaged range (2.5 < |y| < 4.0) The results are RFB (pT < 14 GeV/c, 2.5 < |y| < 4.0) =    0.93 ± 0.29 ± 0.08, 0.86 ± 0.29 ± 0.10,   1.55 ± 0.84 ± 0.59, inclusive, prompt, from b, where the first uncertainties are statistical and the second systematic The ratios RFB for inclusive ψ(2S) production as functions of y and pT are shown in figure For comparison, the plots also show the results for inclusive J/ψ production [19] and the theoretical predictions for ψ(2S) [3–5] The uncertainties for the theoretical predictions are obtained by taking into account minimum and maximum nuclear shadowing effects, with many of them cancelling in the ratios Calculations in ref [3] are based on the Leading Order Colour Singlet Model (LO CSM) [42, 43], taking into account the modification effects of the gluon distribution function in nuclei with the parameterisation EPS09 [2] or nDSg [44] The nextto-leading order Colour Evaporation Model (NLO CEM) [45] is used in ref [5], considering parton shadowing with the EPS09 parameterisation Reference [4] provides theoretical predictions of a coherent parton energy loss effect both in initial and final states, with or without additional parton shadowing effects according to EPS09 The single free parameter q0 in this model is 0.055 (0.075) GeV2/fm when parton shadowing in the EPS09 parameterisation is (not) taken into account Within uncertainties the measurements agree with all these calculations To obtain the nuclear modification factor RpPb , the ψ(2S) production cross-section in pp collisions at TeV is needed, which is not yet available However, it is reasonable to assume that J/ψ J/ψ σpp (5 TeV) ψ(2S) σpp = (5 TeV) σpp (7 TeV) ψ(2S) σpp , (6.2) (7 TeV) where σpp indicates the production cross-section of J/ψ or ψ(2S) in pp collisions The systematic uncertainty due to this assumption is taken to be negligible compared with the statistical uncertainties in this analysis The ratio R of nuclear matter effects between –9– JHEP03(2016)133 Table Production cross-sections σ(bb) of bb pairs in pPb collisions obtained from the production cross-sections of J/ψ and ψ(2S) from b The superscript ψ denotes J/ψ or ψ(2S) The first uncertainties are statistical, the second are systematic, and the third are due to the production branching fractions The last row gives the average of the J/ψ and ψ(2S) results taking account of their correlation The correlated and uncorrelated uncertainties are provided separately R FB R FB Inclusive ψ(2S ) 2.5 EPS09 LO EPS09 NLO nDSg LO E loss E loss + EPS09 NLO 1.5 Inclusive J/ ψ Inclusive ψ(2S ) Inclusive J/ ψ EPS09 NLO 2.5 E loss p T < 14 GeV/c 2.5 < |y| < 4.0 E loss + EPS09 NLO LHCb pPb sNN = TeV 1.5 1 0.5 0.5 LHCb pPb sNN = TeV 0 10 |y | p [GeV/c ] T Figure Forward-backward production ratios RFB as functions of (left) |y| and (right) pT for inclusive ψ(2S) mesons, together with inclusive J/ψ results [19] and the theoretical predictions [3– 5], only some of which are available for |y| For ψ(2S) results, the inner error bars (delimited by the horizontal lines) show the statistical uncertainties; the outer ones show the statistical and systematic uncertainties added in quadrature For J/ψ results, only total uncertainties are shown ψ(2S) and J/ψ can then be determined as ψ(2S) R≡ RpPb J/ψ RpPb ψ(2S) ψ(2S) = σpPb (5 TeV) J/ψ σpPb (5 TeV) ψ(2S) J/ψ × σpp (5 TeV) ψ(2S) σpp (5 TeV) = σpPb (5 TeV) J/ψ σpPb (5 TeV) J/ψ × σpp (7 TeV) ψ(2S) σpp , (6.3) (7 TeV) J/ψ where RpPb and RpPb are the nuclear modification factors for ψ(2S) and J/ψ The ratio R indicates whether there is relative suppression between ψ(2S) and J/ψ production in the collisions If R is less than unity, it suggests that the suppression of ψ(2S) mesons due to nuclear matter effects in pPb collisions is stronger than that of J/ψ mesons Using previous LHCb measurements [19, 34, 46], the values of R for prompt ψ(2S), ψ(2S) from b and inclusive ψ(2S) are calculated The results are shown in figure 5, together with those from ALICE [21] and PHENIX [18] The LHCb measurement is consistent with ALICE, which is in a comparable kinematic range All results suggest a stronger suppression for prompt ψ(2S) mesons than that for prompt J/ψ mesons ψ(2S) J/ψ The nuclear modification factor of ψ(2S), RpPb , can be expressed in terms of RpPb and R ψ(2S) J/ψ RpPb = RpPb × R (6.4) J/ψ The nuclear modification factor RpPb was determined in a previous measurement [19] The result for inclusive ψ(2S) is shown in figure For comparison, the inclusive J/ψ result from previous measurements [19] and the result from ALICE [21] are also shown in the plot The LHCb measurement is consistent with ALICE The results for prompt ψ(2S) and ψ(2S) from b are shown in figure 7, suggesting that in pPb collisions the suppression of prompt ψ(2S) mesons is stronger than that of prompt J/ψ mesons For ψ(2S) from b, no conclusion can be made because of the limited sample size Figure also shows several theoretical predictions [3–5, 47], where only those from ref [47] are available for ψ(2S) from b For prompt ψ(2S), stronger suppression is seen in the data than expected by the – 10 – JHEP03(2016)133 0 R R 1.6 1.4 LHCb pPb sNN = TeV 1.2 p T < 14 GeV/ c 1.6 1.4 LHCb pPb sNN = TeV 1.2 p T < 14 GeV/ c 1 0.8 0.8 0.6 0.6 0.4 0.4 LHCb, prompt ψ (2S ) LHCb, ψ (2S ) from b 0.2 LHCb, sNN = TeV ALICE, sNN = TeV PHENIX, sNN = 0.2 TeV -2 Inclusive ψ(2S) -4 y -2 y R pPb Figure Ratio (left) between nuclear modification factors of ψ(2S) and J/ψ as a function of y for prompt ψ(2S) mesons and ψ(2S) from b The blue triangles represent prompt ψ(2S) and the red rectangles indicate ψ(2S) from b Ratio (right) between nuclear modification factors of ψ(2S) and J/ψ as a function of y for inclusive ψ(2S) mesons The black dots show the LHCb result, the hollow √ circles indicate the ALICE result, and the yellow triangle is the PHENIX result at sNN = 0.2 TeV The inner error bars (delimited by the horizontal lines) show the statistical uncertainties; the outer ones show the statistical and systematic uncertainties added in quadrature Only total uncertainties are shown for the ALICE result 1.8 LHCb, inclusive ψ (2 S ) 1.6 LHCb pPb sNN = TeV LHCb, inclusive J/ ψ 1.4 p T < 14 GeV/ c ALICE, inclusive ψ (2 S ) 1.2 0.8 0.6 0.4 0.2 -4 -2 y Figure Nuclear modification factor RpPb as a function of y for inclusive ψ(2S) and J/ψ mesons The black dots represent the ψ(2S) result, the red squares indicate the J/ψ result, and the blue hollow circles show the ALICE result for ψ(2S) The inner error bars (delimited by the horizontal lines) show the statistical uncertainties; the outer ones show the statistical and systematic uncertainties added in quadrature Only total uncertainties are shown for the ALICE result theoretical calculations mentioned above Final-state effects, such as the interaction of the cc pair with the dense medium created in the collisions, could be involved [48] Conclusions The production cross-sections of prompt ψ(2S) mesons and those from b-hadron decays are studied in pPb collisions with the LHCb detector The nucleon-nucleon centre-of-mass √ energy in the collisions is sNN = TeV The measurement is performed as a function of – 11 – JHEP03(2016)133 -4 0.2 1.6 R pPb R pPb 1.8 LHCb, prompt ψ (2S ) LHCb, prompt J/ ψ LHCb pPb sNN = TeV 1.6 EPS09 LO EPS09 NLO nDSg LO E loss E loss + EPS09 NLO 1.4 1.2 1.8 1.2 0.8 0.8 0.6 0.6 0.4 EPS09 LO nDSg LO 1.4 0.2 LHCb, ψ(2S ) from b LHCb, J/ ψ from b LHCb pPb sNN = TeV 0.4 0.2 p T < 14 GeV/ c -2 y p T < 14 GeV/ c -4 -2 y Figure Nuclear modification factor RpPb as a function of y for (left) prompt ψ(2S) and (right) ψ(2S) from b, together with the theoretical predictions from (yellow dashed line and brown band) refs [3, 47], (blue band) ref [5], and (green solid and blue dash-dotted lines) ref [4], where only those from ref [47] are available for ψ(2S) from b The inner error bars (delimited by the horizontal lines) show the statistical uncertainties; the outer ones show the statistical and systematic uncertainties added in quadrature the transverse momentum and rapidity of ψ(2S) mesons in the region pT < 14 GeV/c and 1.5 < y < 4.0 (forward) and −5.0 < y < −2.5 (backward) The bb production cross-sections in pPb collisions are extracted using the results of ψ(2S) from b and J/ψ from b The forward-backward production ratio RFB is determined separately for prompt ψ(2S) mesons and those from b-hadron decays These results show agreement within uncertainties with available theoretical predictions The nuclear modification factor RpPb is also determined separately for prompt ψ(2S) mesons and ψ(2S) from b These results show that prompt ψ(2S) mesons are significantly more suppressed than prompt J/ψ mesons in the backward region; the results are not well described by theoretical predictions based on shadowing and energy loss mechanisms Acknowledgments We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC We thank the technical and administrative staff at the LHCb institutes We acknowledge support from CERN and from the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FANO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (U.S.A.) We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (U.S.A.) We are indebted to the communities behind the multiple open source software packages on which we depend Individual groups or members have received support from AvH – 12 – JHEP03(2016)133 -4 Foundation (Germany), EPLANET, Marie Sklodowska-Curie Actions and ERC (European Union), Conseil G´en´eral de Haute-Savoie, Labex ENIGMASS and OCEVU, R´egion Auvergne (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal and GENCAT (Spain), The Royal Society, Royal Commission for the Exhibition of 1851 and the Leverhulme Trust (United Kingdom) Open Access This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited [1] T Matsui and H Satz, J/ψ Suppression by quark-gluon Plasma Formation, Phys Lett B 178 (1986) 416 [INSPIRE] [2] K.J Eskola, H Paukkunen and C.A Salgado, EPS09: a new generation of NLO and LO nuclear parton distribution functions, JHEP 04 (2009) 065 [arXiv:0902.4154] [INSPIRE] [3] E.G Ferreiro, F Fleuret, J.P Lansberg and A Rakotozafindrabe, Impact of the nuclear √ modification of the gluon densities on J/ψ production in pPb collisions at sN N = TeV, Phys Rev C 88 (2013) 047901 [arXiv:1305.4569] [INSPIRE] [4] F Arleo and S Peigne, Heavy-quarkonium suppression in p-A collisions from parton energy loss in cold QCD matter, JHEP 03 (2013) 122 [arXiv:1212.0434] [INSPIRE] √ [5] J.L Albacete et al., Predictions for p+Pb collisions at sN N = TeV, Int J Mod Phys E 22 (2013) 1330007 [arXiv:1301.3395] [INSPIRE] [6] A Adeluyi and T Nguyen, Coherent photoproduction of ψ and Υ mesons in ultraperipheral pPb and PbPb collisions at the CERN LHC, Phys Rev C 87 (2013) 027901 [arXiv:1302.4288] [INSPIRE] [7] G.A Chirilli, B.-W Xiao and F Yuan, Inclusive hadron productions in pA collisions, Phys Rev D 86 (2012) 054005 [arXiv:1203.6139] [INSPIRE] [8] G.A Chirilli, High-Energy QCD factorization from DIS to pA collisions, Int J Mod Phys Conf Ser 20 (2012) 200 [arXiv:1209.1614] [INSPIRE] [9] F Arleo, R Kolevatov, S Peign´e and M Rustamova, Centrality and p⊥ dependence of J/ψ suppression in proton-nucleus collisions from parton energy loss, JHEP 05 (2013) 155 [arXiv:1304.0901] [INSPIRE] [10] NuSea collaboration, M.J Leitch et al., Measurement of J/ψ and ψ suppression in p-A collisions at 800 GeV/c, Phys Rev Lett 84 (2000) 3256 [nucl-ex/9909007] [INSPIRE] [11] NA50 collaboration, B Alessandro et al., J/ψ and ψ production and their normal nuclear absorption in proton-nucleus collisions at 400 GeV, Eur Phys J C 48 (2006) 329 [nucl-ex/0612012] [INSPIRE] [12] HERA-B collaboration, I Abt et al., A measurement of the ψ to J/ψ production ratio in 920 GeV proton-nucleus interactions, Eur Phys J C 49 (2007) 545 [hep-ex/0607046] [INSPIRE] – 13 – JHEP03(2016)133 References [13] HERA-B collaboration, I Abt et al., Kinematic distributions and nuclear effects of J/ψ production in 920 GeV fixed-target proton-nucleus collisions, Eur Phys J C 60 (2009) 525 [arXiv:0812.0734] [INSPIRE] [14] BRAHMS collaboration, I Arsene et al., On the evolution of the nuclear modification √ factors with rapidity and centrality in d + Au collisions at sN N = 200 GeV, Phys Rev Lett 93 (2004) 242303 [nucl-ex/0403005] [INSPIRE] [15] PHENIX collaboration, S.S Adler et al., Nuclear modification factors for hadrons at √ forward and backward rapidities in deuteron-gold collisions at sN N = 200 GeV, Phys Rev Lett 94 (2005) 082302 [nucl-ex/0411054] [INSPIRE] [17] PHENIX collaboration, A Adare et al., υ(1S + 2S + 3S) production in d+Au and p + p √ collisions at sN N = 200 GeV and cold-nuclear matter effects, Phys Rev C 87 (2013) 044909 [arXiv:1211.4017] [INSPIRE] [18] PHENIX collaboration, A Adare et al., Nuclear modification of ψ , χc and J/ψ production √ in d+Au collisions at sN N = 200 GeV, Phys Rev Lett 111 (2013) 202301 [arXiv:1305.5516] [INSPIRE] [19] LHCb collaboration, Study of J/ψ production and cold nuclear matter effects in pP b √ collisions at sN N = TeV, JHEP 02 (2014) 072 [arXiv:1308.6729] [INSPIRE] [20] LHCb collaboration, Study of Υ production and cold nuclear matter effects in pPb collisions √ at sN N = TeV, JHEP 07 (2014) 094 [arXiv:1405.5152] [INSPIRE] [21] ALICE collaboration, Suppression of ψ(2S) production in p-Pb collisions at √ sNN = 5.02 TeV, JHEP 12 (2014) 073 [arXiv:1405.3796] [INSPIRE] [22] R Vogt, Are the J/ψ and χc A dependencies the same?, Nucl Phys A 700 (2002) 539 [hep-ph/0107045] [INSPIRE] [23] B.Z Kopeliovich and B.G Zakharov, Quantum effects and color transparency in charmonium photoproduction on nuclei, Phys Rev D 44 (1991) 3466 [INSPIRE] [24] D.C McGlinchey, A.D Frawley and R Vogt, Impact parameter dependence of the nuclear √ modification of J/ψ production in d+Au collisions at sN N = 200 GeV, Phys Rev C 87 (2013) 054910 [arXiv:1208.2667] [INSPIRE] [25] LHCb collaboration, The LHCb detector at the LHC, 2008 JINST S08005 [INSPIRE] [26] LHCb collaboration, LHCb detector performance, Int J Mod Phys A 30 (2015) 1530022 [arXiv:1412.6352] [INSPIRE] [27] T Sjă ostrand, S Mrenna and P.Z Skands, PYTHIA 6.4 physics and manual, JHEP 05 (2006) 026 [hep-ph/0603175] [INSPIRE] [28] LHCb collaboration, Handling of the generation of primary events in Gauss, the LHCb simulation framework, J Phys Conf Ser 331 (2011) 032047 [INSPIRE] [29] D.J Lange, The EvtGen particle decay simulation package, Nucl Instrum Meth A 462 (2001) 152 [INSPIRE] [30] P Golonka and Z Was, PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays, Eur Phys J C 45 (2006) 97 [hep-ph/0506026] [INSPIRE] – 14 – JHEP03(2016)133 [16] PHENIX collaboration, A Adare et al., Cold nuclear matter effects on J/ψ yields as a √ function of rapidity and nuclear geometry in deuteron-gold collisions at sN N = 200 GeV, Phys Rev Lett 107 (2011) 142301 [arXiv:1010.1246] [INSPIRE] [31] Geant4 collaboration, J Allison et al., GEANT4 developments and applications, IEEE Trans Nucl Sci 53 (2006) 270 [32] GEANT4 collaboration, S Agostinelli et al., GEANT4: a simulation toolkit, Nucl Instrum Meth A 506 (2003) 250 [INSPIRE] [36] Particle Data Group collaboration, K.A Olive et al., Review of particle physics, Chin Phys C 38 (2014) 090001 [INSPIRE] [37] LHCb collaboration, Precision luminosity measurements at LHCb, 2014 JINST P12005 [arXiv:1410.0149] [INSPIRE] [38] T Skwarnicki, A study of the radiative cascade transitions between the Υ and Υ resonances, Ph.D thesis, Institute of Nuclear Physics, Krakow, Poland (1986), DESY-F31-86-02 [INSPIRE] [39] W Qian, J/ψ production study at the LHCb experiment, CERN-THESIS-2010-307 (2010) [40] M Pivk and F.R Le Diberder, SPlot: a statistical tool to unfold data distributions, Nucl Instrum Meth A 555 (2005) 356 [physics/0402083] [INSPIRE] [41] LHCb collaboration, Measurement of the track reconstruction efficiency at LHCb, 2015 JINST 10 P02007 [arXiv:1408.1251] [INSPIRE] [42] C.-H Chang, Hadronic production of J/ψ associated with a gluon, Nucl Phys B 172 (1980) 425 [INSPIRE] [43] R Baier and R Ruckl, Hadronic production of J/ψ and Υ: transverse momentum distributions, Phys Lett B 102 (1981) 364 [INSPIRE] [44] D de Florian and R Sassot, Nuclear parton distributions at next-to-leading order, Phys Rev D 69 (2004) 074028 [hep-ph/0311227] [INSPIRE] [45] M Glă uck, J.F Owens and E Reya, Gluon contribution to hadronic J/ψ production, Phys Rev D 17 (1978) 2324 [INSPIRE] √ [46] LHCb collaboration, Measurement of ψ(2S) meson production in pp collisions at s = TeV, Eur Phys J C 72 (2012) 2100 [arXiv:1204.1258] [INSPIRE] [47] Z Conesa del Valle, E.G Ferreiro, F Fleuret, J.P Lansberg and A Rakotozafindrabe, √ Open-beauty production in pPb collisions at sN N = TeV: effect of the gluon nuclear densities, arXiv:1402.1747 [INSPIRE] [48] E.G Ferreiro, Excited charmonium suppression in proton-nucleus collisions as a consequence of comovers, Phys Lett B 749 (2015) 98 [arXiv:1411.0549] [INSPIRE] – 15 – JHEP03(2016)133 [33] LHCb collaboration, The LHCb simulation application, Gauss: design, evolution and experience, J Phys Conf Ser 331 (2011) 032023 [INSPIRE] √ [34] LHCb collaboration, Measurement of J/ψ production in pp collisions at s = TeV, Eur Phys J C 71 (2011) 1645 [arXiv:1103.0423] [INSPIRE] √ [35] LHCb collaboration, Production of J/ψ and Υ mesons in pp collisions at s = TeV, JHEP 06 (2013) 064 [arXiv:1304.6977] [INSPIRE] The LHCb collaboration – 16 – JHEP03(2016)133 R Aaij39 , C Abell´an Beteta41 , B Adeva38 , M Adinolfi47 , A Affolder53 , Z Ajaltouni5 , S Akar6 , J Albrecht10 , F Alessio39 , M Alexander52 , S Ali42 , G Alkhazov31 , P Alvarez Cartelle54 , A.A Alves Jr58 , S Amato2 , S Amerio23 , Y Amhis7 , L An3,40 , L Anderlini18 , G Andreassi40 , M Andreotti17,g , J.E Andrews59 , R.B Appleby55 , O Aquines Gutierrez11 , F Archilli39 , P d’Argent12 , A Artamonov36 , M Artuso60 , E Aslanides6 , G Auriemma26,n , M Baalouch5 , S Bachmann12 , J.J Back49 , A Badalov37 , C Baesso61 , W Baldini17,39 , R.J Barlow55 , C Barschel39 , S Barsuk7 , W Barter39 , V Batozskaya29 , V Battista40 , A Bay40 , L Beaucourt4 , J Beddow52 , F Bedeschi24 , I Bediaga1 , L.J Bel42 , V Bellee40 , N Belloli21,k , I Belyaev32 , E Ben-Haim8 , G Bencivenni19 , S Benson39 , J Benton47 , A Berezhnoy33 , R Bernet41 , A Bertolin23 , F Betti15 , M.-O Bettler39 , M van Beuzekom42 , S Bifani46 , P Billoir8 , T Bird55 , A Birnkraut10 , A Bizzeti18,i , T Blake49 , F Blanc40 , J Blouw11 , S Blusk60 , V Bocci26 , A Bondar35 , N Bondar31,39 , W Bonivento16 , A Borgheresi21,k , S Borghi55 , M Borisyak66 , M Borsato38 , T.J.V Bowcock53 , E Bowen41 , C Bozzi17,39 , S Braun12 , M Britsch12 , T Britton60 , J Brodzicka55 , N.H Brook47 , E Buchanan47 , C Burr55 , A Bursche2 , J Buytaert39 , S Cadeddu16 , R Calabrese17,g , M Calvi21,k , M Calvo Gomez37,p , P Campana19 , D Campora Perez39 , L Capriotti55 , A Carbone15,e , G Carboni25,l , R Cardinale20,j , A Cardini16 , P Carniti21,k , L Carson51 , K Carvalho Akiba2 , G Casse53 , L Cassina21,k , L Castillo Garcia40 , M Cattaneo39 , Ch Cauet10 , G Cavallero20 , R Cenci24,t , M Charles8 , Ph Charpentier39 , M Chefdeville4 , S Chen55 , S.-F Cheung56 , N Chiapolini41 , M Chrzaszcz41,27 , X Cid Vidal39 , G Ciezarek42 , P.E.L Clarke51 , M Clemencic39 , H.V Cliff48 , J Closier39 , V Coco39 , J Cogan6 , E Cogneras5 , V Cogoni16,f , L Cojocariu30 , G Collazuol23,r , P Collins39 , A Comerma-Montells12 , A Contu39 , A Cook47 , M Coombes47 , S Coquereau8 , G Corti39 , M Corvo17,g , B Couturier39 , G.A Cowan51 , D.C Craik51 , A Crocombe49 , M Cruz Torres61 , S Cunliffe54 , R Currie54 , C D’Ambrosio39 , E Dall’Occo42 , J Dalseno47 , P.N.Y David42 , A Davis58 , O De Aguiar Francisco2 , K De Bruyn6 , S De Capua55 , M De Cian12 , J.M De Miranda1 , L De Paula2 , P De Simone19 , C.-T Dean52 , D Decamp4 , M Deckenhoff10 , L Del Buono8 , N D´el´eage4 , M Demmer10 , D Derkach66 , O Deschamps5 , F Dettori39 , B Dey22 , A Di Canto39 , F Di Ruscio25 , H Dijkstra39 , S Donleavy53 , F Dordei39 , M Dorigo40 , A Dosil Su´arez38 , A Dovbnya44 , K Dreimanis53 , L Dufour42 , G Dujany55 , K Dungs39 , P Durante39 , R Dzhelyadin36 , A Dziurda27 , A Dzyuba31 , S Easo50,39 , U Egede54 , V Egorychev32 , S Eidelman35 , S Eisenhardt51 , U Eitschberger10 , R Ekelhof10 , L Eklund52 , I El Rifai5 , Ch Elsasser41 , S Ely60 , S Esen12 , H.M Evans48 , T Evans56 , A Falabella15 , C Fă arber39 , N Farley46 , S Farry53 , R Fay53 , D Fazzini21,k , D Ferguson51 , V Fernandez Albor38 , F Ferrari15 , F Ferreira Rodrigues1 , M Ferro-Luzzi39 , S Filippov34 , M Fiore17,39,g , M Fiorini17,g , M Firlej28 , C Fitzpatrick40 , T Fiutowski28 , F Fleuret7,b , K Fohl39 , P Fol54 , M Fontana16 , F Fontanelli20,j , D C Forshaw60 , R Forty39 , M Frank39 , C Frei39 , M Frosini18 , J Fu22 , E Furfaro25,l , A Gallas Torreira38 , D Galli15,e , S Gallorini23 , S Gambetta51 , M Gandelman2 , P Gandini56 , Y Gao3 , J Garc´ıa Pardi˜ nas38 , J Garra Tico48 , 37 37 39 10 L Garrido , D Gascon , C Gaspar , L Gavardi , G Gazzoni , D Gerick12 , E Gersabeck12 , M Gersabeck55 , T Gershon49 , Ph Ghez4 , S Gian`ı40 , V Gibson48 , O.G Girard40 , L Giubega30 , V.V Gligorov39 , C Găobel61 , D Golubkov32 , A Golutvin54,39 , A Gomes1,a , C Gotti21,k , M Grabalosa G´andara5 , R Graciani Diaz37 , L.A Granado Cardoso39 , E Graug´es37 , E Graverini41 , G Graziani18 , A Grecu30 , P Griffith46 , L Grillo12 , O Gră unberg64 , B Gui60 , 34 36,39 39 56 E Gushchin , Yu Guz , T Gys , T Hadavizadeh , C Hadjivasiliou60 , G Haefeli40 , C Haen39 , S.C Haines48 , S Hall54 , B Hamilton59 , X Han12 , S Hansmann-Menzemer12 , N Harnew56 , S.T Harnew47 , J Harrison55 , J He39 , T Head40 , V Heijne42 , A Heister9 , – 17 – JHEP03(2016)133 K Hennessy53 , P Henrard5 , L Henry8 , J.A Hernando Morata38 , E van Herwijnen39 , M Heß64 , A Hicheur2 , D Hill56 , M Hoballah5 , C Hombach55 , L Hongming40 , W Hulsbergen42 , T Humair54 , M Hushchyn66 , N Hussain56 , D Hutchcroft53 , D Hynds52 , M Idzik28 , P Ilten57 , R Jacobsson39 , A Jaeger12 , J Jalocha56 , E Jans42 , A Jawahery59 , M John56 , D Johnson39 , C.R Jones48 , C Joram39 , B Jost39 , N Jurik60 , S Kandybei44 , W Kanso6 , M Karacson39 , T.M Karbach39,† , S Karodia52 , M Kecke12 , M Kelsey60 , I.R Kenyon46 , M Kenzie39 , T Ketel43 , E Khairullin66 , B Khanji21,39,k , C Khurewathanakul40 , T Kirn9 , S Klaver55 , K Klimaszewski29 , O Kochebina7 , M Kolpin12 , I Komarov40 , R.F Koopman43 , P Koppenburg42,39 , M Kozeiha5 , L Kravchuk34 , K Kreplin12 , M Kreps49 , P Krokovny35 , F Kruse10 , W Krzemien29 , W Kucewicz27,o , M Kucharczyk27 , V Kudryavtsev35 , A K Kuonen40 , K Kurek29 , T Kvaratskheliya32 , D Lacarrere39 , G Lafferty55,39 , A Lai16 , D Lambert51 , G Lanfranchi19 , C Langenbruch49 , B Langhans39 , T Latham49 , C Lazzeroni46 , R Le Gac6 , J van Leerdam42 , J.-P Lees4 , R Lef`evre5 , A Leflat33,39 , J Lefran¸cois7 , E Lemos Cid38 , O Leroy6 , T Lesiak27 , B Leverington12 , Y Li7 , T Likhomanenko66,65 , M Liles53 , R Lindner39 , C Linn39 , F Lionetto41 , B Liu16 , X Liu3 , D Loh49 , I Longstaff52 , J.H Lopes2 , D Lucchesi23,r , M Lucio Martinez38 , H Luo51 , A Lupato23 , E Luppi17,g , O Lupton56 , A Lusiani24 , F Machefert7 , F Maciuc30 , O Maev31 , K Maguire55 , S Malde56 , A Malinin65 , G Manca7 , G Mancinelli6 , P Manning60 , A Mapelli39 , J Maratas5 , J.F Marchand4 , U Marconi15 , C Marin Benito37 , P Marino24,39,t , J Marks12 , G Martellotti26 , M Martin6 , M Martinelli40 , D Martinez Santos38 , F Martinez Vidal67 , D Martins Tostes2 , L.M Massacrier7 , A Massafferri1 , R Matev39 , A Mathad49 , Z Mathe39 , C Matteuzzi21 , A Mauri41 , B Maurin40 , A Mazurov46 , M McCann54 , J McCarthy46 , A McNab55 , R McNulty13 , B Meadows58 , F Meier10 , M Meissner12 , D Melnychuk29 , M Merk42 , A Merli22,u , E Michielin23 , D.A Milanes63 , M.-N Minard4 , D.S Mitzel12 , J Molina Rodriguez61 , I.A Monroy63 , S Monteil5 , M Morandin23 , P Morawski28 , A Mord`a6 , M.J Morello24,t , J Moron28 , A.B Morris51 , R Mountain60 , F Muheim51 , D Mă uller55 , J Mă uller10 , K Mă uller41 , 10 15 40 47 40 50 V Mă uller , M Mussini , B Muster , P Naik , T Nakada , R Nandakumar , A Nandi56 , I Nasteva2 , M Needham51 , N Neri22 , S Neubert12 , N Neufeld39 , M Neuner12 , A.D Nguyen40 , C Nguyen-Mau40,q , V Niess5 , S Nieswand9 , R Niet10 , N Nikitin33 , T Nikodem12 , A Novoselov36 , D.P O’Hanlon49 , A Oblakowska-Mucha28 , V Obraztsov36 , S Ogilvy52 , O Okhrimenko45 , R Oldeman16,48,f , C.J.G Onderwater68 , B Osorio Rodrigues1 , J.M Otalora Goicochea2 , A Otto39 , P Owen54 , A Oyanguren67 , A Palano14,d , F Palombo22,u , M Palutan19 , J Panman39 , A Papanestis50 , M Pappagallo52 , L.L Pappalardo17,g , C Pappenheimer58 , W Parker59 , C Parkes55 , G Passaleva18 , G.D Patel53 , M Patel54 , C Patrignani20,j , A Pearce55,50 , A Pellegrino42 , G Penso26,m , M Pepe Altarelli39 , S Perazzini15,e , P Perret5 , L Pescatore46 , K Petridis47 , A Petrolini20,j , M Petruzzo22 , E Picatoste Olloqui37 , B Pietrzyk4 , M Pikies27 , D Pinci26 , A Pistone20 , A Piucci12 , S Playfer51 , M Plo Casasus38 , T Poikela39 , F Polci8 , A Poluektov49,35 , I Polyakov32 , E Polycarpo2 , A Popov36 , D Popov11,39 , B Popovici30 , C Potterat2 , E Price47 , J.D Price53 , J Prisciandaro38 , A Pritchard53 , C Prouve47 , V Pugatch45 , A Puig Navarro40 , G Punzi24,s , W Qian56 , R Quagliani7,47 , B Rachwal27 , J.H Rademacker47 , M Rama24 , M Ramos Pernas38 , M.S Rangel2 , I Raniuk44 , G Raven43 , F Redi54 , S Reichert55 , A.C dos Reis1 , V Renaudin7 , S Ricciardi50 , S Richards47 , M Rihl39 , K Rinnert53,39 , V Rives Molina37 , P Robbe7,39 , A.B Rodrigues1 , E Rodrigues55 , J.A Rodriguez Lopez63 , P Rodriguez Perez55 , A Rogozhnikov66 , S Roiser39 , V Romanovsky36 , A Romero Vidal38 , J W Ronayne13 , M Rotondo23 , T Ruf39 , P Ruiz Valls67 , J.J Saborido Silva38 , N Sagidova31 , B Saitta16,f , V Salustino Guimaraes2 , C Sanchez Mayordomo67 , B Sanmartin Sedes38 , R Santacesaria26 , C Santamarina Rios38 , M Santimaria19 , E Santovetti25,l , A Sarti19,m , C Satriano26,n , 10 11 12 13 14 15 16 17 18 19 20 21 22 Centro Brasileiro de Pesquisas F´ısicas (CBPF), Rio de Janeiro, Brazil Universidade Federal Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil Center for High Energy Physics, Tsinghua University, Beijing, China LAPP, Universit´e Savoie Mont-Blanc, CNRS/IN2P3, Annecy-Le-Vieux, France Clermont Universit´e, Universit´e Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand, France CPPM, Aix-Marseille Universit´e, CNRS/IN2P3, Marseille, France LAL, Universit´e Paris-Sud, CNRS/IN2P3, Orsay, France LPNHE, Universit´e Pierre et Marie Curie, Universit´e Paris Diderot, CNRS/IN2P3, Paris, France I Physikalisches Institut, RWTH Aachen University, Aachen, Germany Fakultă at Physik, Technische Universită at Dortmund, Dortmund, Germany Max-Planck-Institut fă ur Kernphysik (MPIK), Heidelberg, Germany Physikalisches Institut, Ruprecht-Karls-Universită at Heidelberg, Heidelberg, Germany School of Physics, University College Dublin, Dublin, Ireland Sezione INFN di Bari, Bari, Italy Sezione INFN di Bologna, Bologna, Italy Sezione INFN di Cagliari, Cagliari, Italy Sezione INFN di Ferrara, Ferrara, Italy Sezione INFN di Firenze, Firenze, Italy Laboratori Nazionali dell’INFN di Frascati, Frascati, Italy Sezione INFN di Genova, Genova, Italy Sezione INFN di Milano Bicocca, Milano, Italy Sezione INFN di Milano, Milano, Italy – 18 – JHEP03(2016)133 A Satta25 , D.M Saunders47 , D Savrina32,33 , S Schael9 , M Schiller39 , H Schindler39 , M Schlupp10 , M Schmelling11 , T Schmelzer10 , B Schmidt39 , O Schneider40 , A Schopper39 , M Schubiger40 , M.-H Schune7 , R Schwemmer39 , B Sciascia19 , A Sciubba26,m , A Semennikov32 , A Sergi46 , N Serra41 , J Serrano6 , L Sestini23 , P Seyfert21 , M Shapkin36 , I Shapoval17,44,g , Y Shcheglov31 , T Shears53 , L Shekhtman35 , V Shevchenko65 , A Shires10 , B.G Siddi17 , R Silva Coutinho41 , L Silva de Oliveira2 , G Simi23,s , M Sirendi48 , N Skidmore47 , T Skwarnicki60 , E Smith54 , I.T Smith51 , J Smith48 , M Smith55 , H Snoek42 , M.D Sokoloff58,39 , F.J.P Soler52 , F Soomro40 , D Souza47 , B Souza De Paula2 , B Spaan10 , P Spradlin52 , S Sridharan39 , F Stagni39 , M Stahl12 , S Stahl39 , S Stefkova54 , O Steinkamp41 , O Stenyakin36 , S Stevenson56 , S Stoica30 , S Stone60 , B Storaci41 , S Stracka24,t , M Straticiuc30 , U Straumann41 , L Sun58 , W Sutcliffe54 , K Swientek28 , S Swientek10 , V Syropoulos43 , M Szczekowski29 , T Szumlak28 , S T’Jampens4 , A Tayduganov6 , T Tekampe10 , G Tellarini17,g , F Teubert39 , C Thomas56 , E Thomas39 , J van Tilburg42 , V Tisserand4 , M Tobin40 , J Todd58 , S Tolk43 , L Tomassetti17,g , D Tonelli39 , S Topp-Joergensen56 , E Tournefier4 , S Tourneur40 , K Trabelsi40 , M Traill52 , M.T Tran40 , M Tresch41 , A Trisovic39 , A Tsaregorodtsev6 , P Tsopelas42 , N Tuning42,39 , A Ukleja29 , A Ustyuzhanin66,65 , U Uwer12 , C Vacca16,39,f , V Vagnoni15 , G Valenti15 , A Vallier7 , R Vazquez Gomez19 , P Vazquez Regueiro38 , C V´ azquez Sierra38 , S Vecchi17 , M van Veghel43 , J.J Velthuis47 , M Veltri18,h , G Veneziano40 , M Vesterinen12 , B Viaud7 , D Vieira2 , M Vieites Diaz38 , X Vilasis-Cardona37,p , V Volkov33 , A Vollhardt41 , D Voong47 , A Vorobyev31 , V Vorobyev35 , C Voß64 , J.A de Vries42 , R Waldi64 , C Wallace49 , R Wallace13 , J Walsh24 , J Wang60 , D.R Ward48 , N.K Watson46 , D Websdale54 , A Weiden41 , M Whitehead39 , J Wicht49 , G Wilkinson56,39 , M Wilkinson60 , M Williams39 , M.P Williams46 , M Williams57 , T Williams46 , F.F Wilson50 , J Wimberley59 , J Wishahi10 , W Wislicki29 , M Witek27 , G Wormser7 , S.A Wotton48 , K Wraight52 , S Wright48 , K Wyllie39 , Y Xie62 , Z Xu40 , Z Yang3 , H Yin62 , J Yu62 , X Yuan35 , O Yushchenko36 , M Zangoli15 , M Zavertyaev11,c , L Zhang3 , Y Zhang3 , A Zhelezov12 , A Zhokhov32 , L Zhong3 , V Zhukov9 , S Zucchelli15 23 24 25 26 27 28 29 30 31 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 – 19 – JHEP03(2016)133 32 Sezione INFN di Padova, Padova, Italy Sezione INFN di Pisa, Pisa, Italy Sezione INFN di Roma Tor Vergata, Roma, Italy Sezione INFN di Roma La Sapienza, Roma, Italy Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Krak´ ow, Poland AGH - University of Science and Technology, Faculty of Physics and Applied Computer Science, Krak´ ow, Poland National Center for Nuclear Research (NCBJ), Warsaw, Poland Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN), Moscow, Russia Budker Institute of Nuclear Physics (SB RAS) and Novosibirsk State University, Novosibirsk, Russia Institute for High Energy Physics (IHEP), Protvino, Russia Universitat de Barcelona, Barcelona, Spain Universidad de Santiago de Compostela, Santiago de Compostela, Spain European Organization for Nuclear Research (CERN), Geneva, Switzerland Ecole Polytechnique F´ed´erale de Lausanne (EPFL), Lausanne, Switzerland Physik-Institut, Universită at Ză urich, Ză urich, Switzerland Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, The Netherlands NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine University of Birmingham, Birmingham, United Kingdom H.H Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom Department of Physics, University of Warwick, Coventry, United Kingdom STFC Rutherford Appleton Laboratory, Didcot, United Kingdom School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom Imperial College London, London, United Kingdom School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom Department of Physics, University of Oxford, Oxford, United Kingdom Massachusetts Institute of Technology, Cambridge, MA, United States University of Cincinnati, Cincinnati, OH, United States University of Maryland, College Park, MD, United States Syracuse University, Syracuse, NY, United States Pontif´ıcia Universidade Cat´ olica Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil, associated to2 Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China, associated to3 Departamento de Fisica , Universidad Nacional de Colombia, Bogota, Colombia, associated to Institut fă ur Physik, Universită at Rostock, Rostock, Germany, associated to 12 National Research Centre Kurchatov Institute, Moscow, Russia, associated to 32 Yandex School of Data Analysis, Moscow, Russia, associated to32 Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC, Valencia, Spain, associated to37 Van Swinderen Institute, University of Groningen, Groningen, The Netherlands, associated to 42 a b c d e f g h i j l m n o p q r s t u – 20 – JHEP03(2016)133 k Universidade Federal Triˆ angulo Mineiro (UFTM), Uberaba-MG, Brazil Laboratoire Leprince-Ringuet, Palaiseau, France P.N Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia Universit` a di Bari, Bari, Italy Universit` a di Bologna, Bologna, Italy Universit` a di Cagliari, Cagliari, Italy Universit` a di Ferrara, Ferrara, Italy Universit` a di Urbino, Urbino, Italy Universit` a di Modena e Reggio Emilia, Modena, Italy Universit` a di Genova, Genova, Italy Universit` a di Milano Bicocca, Milano, Italy Universit` a di Roma Tor Vergata, Roma, Italy Universit` a di Roma La Sapienza, Roma, Italy Universit` a della Basilicata, Potenza, Italy AGH - University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Krak´ ow, Poland LIFAELS, La Salle, Universitat Ramon Llull, Barcelona, Spain Hanoi University of Science, Hanoi, Viet Nam Universit` a di Padova, Padova, Italy Universit` a di Pisa, Pisa, Italy Scuola Normale Superiore, Pisa, Italy Universit` a degli Studi di Milano, Milano, Italy † Deceased ... collaboration, Study of J/ψ production and cold nuclear matter effects in pP b √ collisions at sN N = TeV, JHEP 02 (2014) 072 [arXiv:1308.6729] [INSPIRE] [20] LHCb collaboration, Study of Υ production. .. are measured in pPb collisions at sNN = 5.0 2TeV, approximated in the following to TeV The nuclear modification factor RpPb and the forward-backward production ratio RFB are determined in the range... production and cold nuclear matter effects in pPb collisions √ at sN N = TeV, JHEP 07 (2014) 094 [arXiv:1405.5152] [INSPIRE] [21] ALICE collaboration, Suppression of ψ(2S) production in p-Pb collisions